Fifty-two healthy volunteers (27 women and 25 men) between
19 and 45 years old took part in this study. The participants were
young adults and were non-obese. They were sedentary and not
taking medication. They were all nonsmokers and spent regular
times in bed at night (7.5-8.5 h). The subjects did not suffer from
sleep disturbances (apnea and hypopnea index [AHI] < 5, and periodic
leg movements [PLM] during sleep were < 5, as assessed by polysomnography).20,21 Volunteers were submitted to a clinical
examination including blood, urine, and electrocardiogram
tests, which were evaluated by a physician who approved their
participation in the study. Enrolment was voluntary, and the subjects
were informed of the procedures and objectives of the study.
The study was approved by the Committee of Ethics in Research
of the Federal University of São Paulo (0019/08). After
participants were informed about all the stages of this study and
gave their written informed consent.